Solid-state metal oxide transistor-based technology could make it easier and faster to diagnose and tackle COVID-19 and many other diseases.

This approach to diagnosing diseases—engineered by a team from the King Abdullah University of Science and Technology (KAUST)—can detect tiny quantities of biomolecules, such as DNA and COVID-19 spike protein, in less than two minutes.

Solid-state transistors can serve as candidates for directly sensing biomolecules of interest, or analytes, with high sensitivity and selectivity. They can convert interactions between sensor surface and analyte into an amplified electrical signal. Also, they don’t require time-consuming sample preparation steps or specialized equipment.

Thomas Anthopoulos, PhD, professor of material science and engineering at KAUST, and coworkers used solid-state metal oxide transistors with a tunable surface chemistry and exceptional operating characteristics to design a biosensor that had a unique tri-channel configuration. This configuration comprises a central sensing channel flanked by two conventional channels.

The team discovered that an analyte droplet located outside the conventional channel area still triggered some response in a typical metal oxide transistor-based sensor, which inspired them to design the tri-channel device, says Yen-Hung Lin, PhD, who co-led the study.

The researchers successively layered indium oxide and zinc oxide solutions on a support to form a so-called semiconducting heterojunction. Next, they manufactured the electrodes on the heterojunction before depositing another zinc oxide layer on the electron transporting interface. They sequentially anchored a target-specific receptor molecule to modulate the selectivity and butyric acid to prevent direct contact between the sensing channel and the fluids used to disperse the analytes to this top layer.

In addition to detecting various types of DNA and the biotin-binding protein avidin at extremely low concentrations, the biosensor showed ultrasensitivity to the COVID-19 spike protein when target-specific antibody acceptors were immobilized to its surface.

“We did anticipate extreme sensitivity but were not sure whether the analyte–receptor interactions would be strong enough to be sensed with high fidelity. It turned out that it was,” he adds.

The team now plans to build a portable system that could simultaneously test for a variety of pathogens.

“Our platform is ideal for developing sensor arrays featuring different types of receptors to detect multiple analytes in a single biosample,” says Anthopoulos.

Featured image: An international research team led by KAUST has engineered a solid-state metal oxide transistor-based technology that can rapidly detect the SARS‑CoV‑2 virus in biosamples. Photo: 2021 KAUST; Xavier Pita